This is based on much reading and personal experience, I am not a physician nor do I play one on TV. :)
Xanax is short lived but powerful. It is also very addictive and once you have been on it for a period of time it is very difficult to stop. I have read that withdrawal can sometimes take up to a year for those on highr doses. The withdrawal symptoms are worse than the ailment you began taking it for.
It is a lifesaver during intense anxiety attacks. It will remove the symptoms usually in 20 minutes or less.
Klonopin has a longer 1/2 life (longer effect) and is (in theory) easier to withdrawal from because of that reason. It seems to me to be more mellow and not as potent as Xanax.
Both are available in generic form so they are cheap as all get out.
Xanax would make me somewhat "loopy" and "silly". It did help me sleep but I would wake with headaches (sometimes severe). After several years of Xanax (at low dosage) I decided to quit cold turkey....not a good idea. After several days I found myself in the doctors office looking for relief and a method to get off Xanax. The Xanax withdrawal symptoms were horrible...insomnia, irritable bowel, increased anxiety, irritability, headaches and jitters.
I discussed switching to Klonopin as a "transition" medication so I could stop the Xanax and then reduce the Klonopin gradually until I was finally benzo free. The doctor agreed that was the best method. It is a method that is suggested by many "benzo-buster" websites. I understand it is much easier to stop Klonopin than Xanax, mostly due to the half-life of each drug.
The Klonopin helps me sleep just as well as the Xanax but I dont have headaches in the morning and the Klonopin lasts longer so I dont wake up as anxious as before. It also doesnt make me feel "loopy" like the Xanax did.
On the down side, it isnt as fast acting for me so I dont use it as a "stop this now" medication. I will start 1/2 doses (tapering down) of the Klonopin Monday.
I hope this info helped. PLEASE discuss this with your physician.
Mike